Blood plasma separation device

ABSTRACT

A device for separating blood plasma from whole blood includes a first reservoir and a second reservoir. The first reservoir is configured to receive a sample of whole blood including red blood cells and includes a collection region and a constricted region. The second reservoir is fluidically connected to the constricted region of the first reservoir, such that, responsive to centrifugal force applied to the device, the sample of whole blood disposed within the first reservoir separates into a first fraction and a second fraction. The first fraction is located in the collection region and includes blood plasma from which substantially all red blood cells have been removed. The second fraction is located in the second reservoir and includes blood plasma and red blood cells that have been removed from the first fraction by the centrifugal force. The constricted region inhibits the second fraction from entering the collection region.

RELATED APPLICATION

The current application claims priority to U.S. Patent Application No.62/722,050 filed on Aug. 23, 2018, the contents of which are herebyfully incorporated by reference.

FIELD

This application relates to separating blood plasma from whole blood.

BACKGROUND

It can be useful to separate blood plasma from whole blood, for exampleto facilitate analysis of one or more components of the blood plasma.

SUMMARY

Blood plasma separation devices, and methods of making and using thesame, are provided herein.

A device for separating blood plasma from whole blood includes a firstreservoir and a second reservoir. The first reservoir is configured toreceive a sample of whole blood including red blood cells. The firstreservoir includes a collection region and a constricted region. Thesecond reservoir is fluidically connected to the constricted region ofthe first reservoir, such that, responsive to centrifugal force appliedto the device, the sample of whole blood disposed within the firstreservoir separates into a first fraction and a second fraction. Thefirst fraction is located in the collection region and includes bloodplasma from which substantially all red blood cells have been removed.The second fraction is located in the second reservoir and includesblood plasma and red blood cells that have been removed from the firstfraction by the centrifugal force. The constricted region inhibits thesecond fraction from entering the collection region.

An outlet can be provided that is fluidically connected to thecollection region. In addition, a channel can fluidically connect theoutlet to the collection region. Such angle can be disposed at an acuteangle relative to the collection region. The channel can be configuredto substantially fill with the first fraction via capillary actionresponsive to termination of the centrifugal force.

The first reservoir can include a sample reservoir and a plasmareservoir fluidically connected to one another. With such arrangements,the sample reservoir can include an inlet configured to receive thesample of whole blood and the plasma reservoir can include thecollection region and the constricted region. The sample reservoir,plasma reservoir, and second reservoir can each include one or morerespective sidewalls and a respective lower surface. A cover (or otherhousing element) can be disposed over the sample reservoir, plasmareservoir, and second reservoir. The respective lower surface of theplasma reservoir can be closer to the cover than are the respectivelower surfaces of the sample reservoir and the second reservoir. Anupper surface of the sample of whole blood disposed within the samplereservoir can be further from the cover than is the lower surface of theplasma reservoir. The sample of whole blood disposed within the samplereservoir can flow upward toward the cover to contact the lower surfaceof the plasma reservoir responsive to the centrifugal force applied tothe device.

In some variations, a first one of the sidewalls of the sample reservoircan be disposed at an angle (e.g., obtuse angle, etc.) angle relative tothe lower surface of the sample reservoir. With such an arrangement,substantially all of the sample of whole blood disposed within thesample reservoir can flow upward along the first one of the sidewalls ofthe sample reservoir responsive to the centrifugal force applied to thedevice.

A portion of the sample of whole blood contacting the lower surface ofthe plasma reservoir can flow downward away from the cover to contactthe lower surface of the second reservoir responsive to the centrifugalforce applied to the device. The portion of the sample of whole bloodcontacting the lower surface of the plasma reservoir can flow downwardalong a first one of the sidewalls of the second reservoir responsive tothe centrifugal force applied to the device.

The first and second fractions can each contact the cover aftertermination of the centrifugal force. The cover can be at leastpartially optically transparent. The cover can include a first aperturevia which the sample reservoir receives the sample of whole blood and asecond aperture via which the first fraction is withdrawn. The firstaperture can be disposed over the sample reservoir. The second aperturecan be disposed over the plasma reservoir. A channel can be providedthat fluidically connects the outlet to the collection region, whereinthe second aperture is located over the channel. The first and secondapertures can each be configured to receive a pipette tip.

The cover can include a vent disposed over the sample reservoir.

The first fraction can substantially fill the plasma reservoirresponsive to the centrifugal force.

The second fraction can substantially fill the second reservoirresponsive to the centrifugal force.

The sample reservoir, the plasma reservoir, and the second reservoir canbe arranged linearly with one another.

A meniscus of the first fraction can be disposed within the collectionregion.

In some variations, at least 75% of the red blood cells in the sample ofwhole blood are removed from the first fraction. In other variations, atleast 99% of the red blood cells in the sample of whole blood areremoved from the first fraction. In still other variations, 100% of thered blood cells in the sample of whole blood are removed from the firstfraction.

The first reservoir can have varying volumes. For example, the firstreservoir can have a volume about 25 μL to about 1 mL, or about 50-500μL, or about 100-250 μL.

The second reservoir can have varying volumes. For example, the secondreservoir can have a volume of about 20-80% of a volume of the firstreservoir, or a volume of about 40-60% of a volume of the firstreservoir.

A rotatable disc can be provided in which the first and secondreservoirs are disposed.

In an interrelated aspect, blood plasma is separated from whole blood byreceiving, by a first reservoir of a device, a sample of whole bloodcomprising red blood cells. The first reservoir includes a collectionregion and a constricted region. A centrifugal force is applied to thedevice to separate the sample of whole blood into a first fraction and asecond fraction. The first fraction is located in the collection regionand includes blood plasma from which substantially all red blood cellshave been removed. The second fraction is located in a second reservoirof the device and includes blood plasma and red blood cells that havebeen removed from the first fraction by the centrifugal force. Theconstricted region inhibits the second fraction from entering thecollection region.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A-1B respectively schematically illustrate plan andcross-sectional views of an exemplary blood plasma separation device,according to various configurations provided herein.

FIGS. 1C-1D schematically illustrates cross-sectional views of theexemplary blood plasma separation device of FIGS. 1A-1B during use,according to various configurations provided herein.

FIGS. 2A-2D schematically illustrate cross-sectional views ofalternative blood plasma separation devices, according to variousconfigurations provided herein.

FIG. 3 schematically illustrates a plan view of another alternativeblood plasma separation device, according to various configurationsprovided herein.

FIGS. 4A-4B schematically illustrate plan and cross-sectionalperspective views of components of another alternative blood plasmaseparation device, according to various configurations provided herein.

FIG. 5 schematically illustrates a plan view of a disc including thedevice of FIGS. 4A-4B, according to various configurations providedherein.

FIG. 6 illustrates an exemplary flow of operations in a method of usingthe devices of FIGS. 1A-5 , according to various configurations providedherein.

FIGS. 7A-7D schematically illustrate plan views of components of a bloodplasma separation device during operations of the method of FIG. 6 ,according to various configurations provided herein.

DETAILED DESCRIPTION

Blood plasma separation devices, and methods of making and using thesame, are provided herein. The present blood plasma separation devicesand methods suitably can be used to separate blood plasma from one ormore other components of a sample of whole blood based on centrifugalforces. For example, the present blood plasma separation devices andmethods can be used to separate blood plasma from blood cells within thesample of whole blood, so as to generate a fraction from whichsubstantially all blood cells have been removed. Such fraction, whichcan primarily contain plasma, can collect within a first reservoir, anda fraction containing blood cells that have been removed can collectwithin a second reservoir. In some configurations provided herein, aconstriction within the device inhibits blood cells from reentering thefraction that primarily contains plasma.

FIGS. 1A-1B respectively schematically illustrate plan andcross-sectional views of an exemplary blood plasma separation device,according to various configurations provided herein. Device 100illustrated in FIGS. 1A-1B can include first reservoir 110 configured toreceive a sample of whole blood comprising red blood cells. Firstreservoir 110 optionally can include collection region 111 andconstricted region 112. Device 100 further can include second reservoir120 that is fluidically connected to constricted region 112 of firstreservoir 110. Optionally, first reservoir 110 and second reservoir 120are arranged linearly with one another, and as a further optioncollection region 111, constricted region 112, and second reservoir 120are arranged linearly with one another.

Optionally, device 100 includes inlet 113 via which first reservoir 110can receive a sample of whole blood. Additionally, or alternatively,device 100 optionally includes outlet 114 via which a fraction primarilycontaining plasma can be withdrawn following centrifugation in a mannersuch as described herein with reference to FIGS. 1C-1D, 6, and 7A-7D.Additionally, or alternatively, device 100 optionally includes vent 115via which air can escape from first reservoir 110 when a sample of wholeblood is received within that reservoir, e.g., via optional inlet 113.Optionally, inlet 113, outlet 114, and/or vent 115 can be defined withincover 116, e.g., as optional first, second, and/or third aperturesdefined through cover 116, one or more of which apertures can beconfigured to receive a pipette tip.

First reservoir 110 and second reservoir 120 can have any suitableconfiguration and include any suitable number of upper surfaces(covers), lower surfaces (covers), and/or sidewalls which respectivelycan be discrete elements or can be integrally formed with one another,for example as described in greater detail herein with reference toFIGS. 2A-2D. In the nonlimiting configuration illustrated in FIG. 1B,first reservoir 110 includes upper surface (first cover) 116,sidewall(s) 117, and lower surface (second cover) 118 together providingan open area 119, and second reservoir 120 includes upper surface (thirdcover) 123, sidewall(s) 121, 122, and lower surface (fourth cover) 124together providing an open area 125. It should be appreciated that termssuch as “upper,” “lower,” “sidewall,” and “cover” are not intended to belimiting of any particular orientation of the devices and methodsprovided herein, but instead to provide helpful terms by which variouscomponents optionally can be referred for the illustrated orientationand configuration. In the configuration illustrated in FIG. 1B, thelower surface 118 and cover 116 of first reservoir 110 are closer to oneanother than the lower surface 124 and cover 123 of second reservoir120. One or more covers of device 100, e.g., one or more of uppersurface 116, upper surface 123, lower surface 118, and/or lower surface124 independently can be at least partially optically transparent.

Optional inlet port (first aperture) 113 can be disposed over a firstregion of open area 119, which is configured to receive a sample ofwhole blood and optionally can be considered to be a sample reservoir.Optional outlet port (second aperture 114) can be disposed over a secondregion of open area 119, which can be considered to be a plasmareservoir and is configured to collect a primarily plasma fraction whichis generated responsive to centrifugal force in the direction indicatedby the large arrow. It should be appreciated that a sample of wholeblood can be introduced into open area 119 of collection region 111 viaany suitable inlet, and is not limited to an aperture through a coverdisposed over open area 119. For example, the sample of whole blood canbe introduced into collection region 111 via a channel configuredsimilarly to channel 330 described with reference to FIG. 3 . It shouldalso be appreciated that a fraction primarily containing blood plasmacan be removed from open area 119 of collection region 111 via anysuitable outlet, and is not limited to an aperture through a coverdisposed over open area 119. For example, the fraction can be removedfrom collection region 111 via a channel configured similarly to channel330 described with reference to FIG. 3 . Such channel optionally caninclude an outlet configured similarly to outlet 314 described withreference to FIG. 3 , or optionally can be connected to another device,for example configured to perform further processing of the fraction.

Responsive to centrifugal force applied to device 100, the sample ofwhole blood disposed within first reservoir 110 separates into a firstfraction and a second fraction. For example, FIGS. 1C-1D schematicallyillustrate a cross-sectional view of the exemplary blood plasmaseparation device of FIGS. 1A-1B during use, e.g., during operations ofthe method of FIG. 6 and similarly as illustrated in FIGS. 7A-7B,according to various configurations provided herein. As illustrated inFIG. 1C, first reservoir 110 can receive a sample 130 of whole blood viaoptional inlet port (aperture) 113. Responsive to centrifugal force inthe direction indicated by the large arrow, for example by spinning adisc that includes device 100 in a manner similar to that illustrated inFIG. 5 , the sample of whole blood separates into a first fraction 131and a second fraction 132 in a manner such as schematically illustratedin FIG. 1D. First fraction 131 can be located at least in collectionregion 111 and can include blood plasma from which substantially all redblood cells have been removed, for example in a manner similar to thatdescribed herein with reference to FIG. 7C. Second fraction 132 can belocated in second reservoir 120 and can include blood plasma and redblood cells that have been removed from the first fraction by thecentrifugal force. As used herein, removal of “substantially all” redblood cells is intended to mean that at least 75% of the red blood cellsin the sample of whole blood are removed from the first fraction, or atleast 99% of the red blood cells in the sample of whole blood areremoved from the first fraction, or 100% of the red blood cells in thesample of whole blood are removed from the first fraction. Suchseparation of red blood cells (and optionally other types of bloodcells) from the blood plasma can be achieved, for example, by applyingsufficient centrifugal force to device 100 for a sufficient amount oftime. For example, a disc in which device 100 is included can be spun ata rate of 1000 or more revolutions per minute (RPM), a rate of 2000 RPMor more, a rate of 3000 RPM or more, or a rate of 4000 RPM or more, fora sufficient amount of time to remove substantially all red blood cellsfrom the sample of whole blood so as to generate first fraction 131.

In some configurations, responsive to the centrifugal force applied tothe device (e.g., via such spinning), optionally a portion of the sampleof whole blood 113 contacting the lower surface 118 of collection region111 flows downward away from cover 116 to contact the lower surface 124of the second reservoir 120. Optionally, first fraction 131substantially fills a portion of the first reservoir 110 responsive tothe centrifugal force, e.g., substantially fills constricted region 112and a portion of collection region 111. Additionally, or alternatively,optionally second fraction 132 substantially fills second reservoir 120responsive to the centrifugal force. As a further or alternative option,first fraction 131 contacts cover 116, and second fraction contactscover 123, after termination of the centrifugal force. Optionally, firstfraction 131 suitably can be removed from first reservoir 110 via anysuitable outlet fluidically connected to collection region 111. Forexample, first fraction 131 can be removed via optional outlet port 114,or via a channel configured similarly to channel 330 described withreference to FIG. 3 which optionally can include an outlet port or canbe connected to another device. As yet another option, first fraction131 can remain within first reservoir 110, e.g., can be optionallyanalyzed, for example via optical analysis through upper surface 116and/or lower surface 118 each of which optionally can be at leastpartially optically transparent.

In various configurations provided herein, constricted region 112optionally inhibits second fraction 132 from entering collection region111, e.g., after the centrifugal force is removed. As such, constrictedregion 112 optionally can inhibit red blood cells (and optionally othertypes of blood cells) within second fraction from reentering the plasmawithin first fraction 131, such that substantially all red blood cellscontinue to be excluded from first fraction 131 even after thecentrifugal force is removed.

The constricted region 112 can for venting of air as well as constrictfluid flow to prevent movement of cells after separation. Theconstricted region 112 can, in some variations, have a cross sectionwith at least one of the dimensions less than 1 mm. The constrictedregion 112 can have a cross-section that is square, rectangular, and/orcircular/semi-circular or any other shape. It is currently 1 mm×0.5 mmbut could be other dimensions that similarly constrain flow.

Additionally, or alternatively, in the exemplary configurationillustrated in FIGS. 1A-1D, open area 119 optionally is shallower than,and positioned higher than, open area 125, and as a result blood cellsthat are forced into second reservoir 120 by centrifugal forces can beinhibited from reentering the plasma of first fraction 131. Optionally,meniscus 133 of first fraction 131 is disposed within collection region111, e.g., such as illustrated in FIG. 1D. For example, meniscus 133 canextend between the upper and lower surfaces 116, 118 of collectionregion 111.

Note that first reservoir 110 (and components thereof) and secondreservoir 120 (and components thereof) can have any suitable volume,configuration, and dimensions. As one nonlimiting example, firstreservoir 110 optionally can have a volume about 25 μL to about 1 mL, orabout 50-500 μL, or about 100-250 μL. Additionally, or alternatively,second reservoir 120 optionally can have a volume of about 20-80% of avolume of first reservoir 110, or a volume of about 40-60% of a volumeof first reservoir 110. For example, second reservoir 120 optionally canbe sized so as to accommodate substantially all of the red blood cellswithin whole blood sample 130, e.g., following separation of that sampleinto first and second fractions.

As noted elsewhere herein, first reservoir 110 and second reservoir 120can have any suitable configuration and include any suitable number ofupper surfaces (covers), lower surfaces (covers), and/or sidewalls whichrespectively can be discrete elements or can be integrally formed withone another. For example, in the nonlimiting example illustrated inFIGS. 1A-1D, optionally the upper surfaces, lower surfaces, andsidewalls can be provided as discrete elements which are suitablycoupled to one another. FIGS. 2A-2D schematically illustratecross-sectional views of alternative blood plasma separation devices,according to various configurations provided herein. Alternative device200 illustrated in FIG. 2A can include upper surfaces, lower surfaces,and sidewalls which are configured similarly as device 100 describedwith reference to FIGS. 1A-1D, but in which some of such elements areintegrally formed with one another. For example, device 200 can includesidewall element 230 within which respective sidewalls of collectionregion 211, constricted region 212, and second reservoir 220 can beintegrally disposed. Device 200 also can include first cover element 240within which respective upper surfaces of collection region 211,constricted region 212, and second reservoir 220 can be integrallydisposed. Device 200 also can include second cover element 250 withinwhich respective lower surfaces of collection region 211, constrictedregion 212, and second reservoir 220 can be integrally disposed.Sidewall element 230, first cover element 240, and second cover element250 can be discrete from one another and suitably coupled to oneanother.

Alternative device 200′ illustrated in FIG. 2B can include uppersurfaces, lower surfaces, and sidewalls which are configured similarlyas device 100 described with reference to FIGS. 1A-1D, but in which someof such elements are integrally formed with one another. For example,device 200′ can include combined sidewall/cover element 250 within whichrespective sidewalls and lower surfaces of collection region 211,constricted region 212, and second reservoir 220 can be integrallydisposed. Device 200 also can include cover element 240 within whichrespective upper surfaces of collection region 211, constricted region212, and second reservoir 220 can be integrally disposed. Combinedsidewall/cover element 250 and cover element 240 can be discrete fromone another and suitably coupled to one another.

Alternative device 200″ illustrated in FIG. 2C can include uppersurfaces, lower surfaces, and sidewalls which are configured similarlyas device 100 described with reference to FIGS. 1A-1D, but in which someof such elements are integrally formed with one another. For example,device 200″ can include combined sidewall/cover element 270 within whichrespective sidewalls and upper surfaces of collection region 211,constricted region 212, and second reservoir 220 can be integrallydisposed. Device 200 also can include cover element 250 within whichrespective lower surfaces of collection region 211, constricted region212, and second reservoir 220 can be integrally disposed. Combinedsidewall/cover element 270 and cover element 250 can be discrete fromone another and suitably coupled to one another.

Alternative device 200′″ illustrated in FIG. 2D can include uppersurfaces, lower surfaces, and sidewalls which are configured similarlyas device 100 described with reference to FIGS. 1A-1D, but in which allof such elements are integrally formed with one another. For example,device 200′ can include combined sidewall/cover element 280 within whichrespective sidewalls, upper surfaces, and lower surfaces of collectionregion 211, constricted region 212, and second reservoir 220 can beintegrally disposed.

As noted elsewhere herein, the first fraction can be removed from thecollection region of the first reservoir using any suitable outletfluidically connected to the collection region, or optionally can beleft in place. Optional outlet port 114 illustrated in FIGS. 1A-1Dprovides one example of such an outlet. Another example is illustratedin FIG. 3 , which schematically illustrates a plan view of anotheralternative blood plasma separation device, according to variousconfigurations provided herein. Device 300 illustrated in FIG. 3includes first reservoir 310 which can be configured to receive a sampleof whole blood comprising red blood cells, and can be configuredsimilarly to first reservoir 110 described with reference to FIGS.1A-1D. For example, first reservoir 310 optionally can includecollection region 311 and constricted region 312. Device 300 further caninclude second reservoir 320 that is fluidically connected toconstricted region 312 of first reservoir 310 and can be configuredsimilarly to second reservoir 120 described with reference to FIGS.1A-1D. Optionally, device 300 includes inlet 313 via which firstreservoir 310 can receive a sample of whole blood in a manner similarlyas inlet 113 described with reference to FIGS. 1A-1D, or other suitablestructure for introducing a sample of whole blood to first reservoir310. Additionally, or alternatively, device 300 optionally includes vent315 via which air can escape from first reservoir 310 when a sample ofwhole blood is received within that reservoir, e.g., via optional inlet313.

Device 300 illustrated in FIG. 3 optionally further includes channel 330which is fluidically connected to the collection region 311. Channel 330optionally is configured to substantially fill with the first fractionvia capillary action responsive to termination of the centrifugal force.In some configurations, optional channel 330 is configured tofluidically connect an outlet 314 to the collection region 311, and thefirst fraction can be withdrawn from collection region 311 via channel330 and outlet 314. In other configurations, optional channel 330 iscoupled to another device (not specifically illustrated) which canreceive the first fraction via the channel. Additionally, oralternatively, channel 330 optionally is disposed at an acute anglerelative to the collection region 311, which can inhibit red blood cellsfrom entering the first fraction within the channel.

Still other configurations can be envisioned. For example, FIGS. 4A-4Bschematically illustrate plan and cross-sectional perspective views ofcomponents of another alternative blood plasma separation device,according to various configurations provided herein. In the exemplaryconfiguration illustrated in FIGS. 4A-4B, device 400 includes firstreservoir 410, second reservoir 420, and channel 430. First reservoir410 includes sample reservoir 416 and plasma reservoir 417 which arefluidically connected to one another. Plasma reservoir 417 optionallycan include collection region 411 and constricted region 412 whichrespectively can be configured similarly as collection region 111 andconstricted region 112 described with reference to FIGS. 1A-1D. Thesample reservoir 416, plasma reservoir 417, and second reservoir 420each can include one or more respective sidewalls and a respective lowersurface, as well as a respective upper surface (omitted in FIG. 4B forclarity), e.g., a cover disposed over the sample reservoir, plasmareservoir, and second reservoir. Any suitable ones of the uppersurfaces, lower surfaces, and sidewalls can be discrete from one anotheror integrally formed with one another, e.g., in a manner similar to thatdescribed with reference to FIGS. 2A-2D. For example, in the nonlimitingexample shown in FIGS. 4A-4B, the sidewalls and lower surfaces of samplereservoir 416, plasma reservoir 417, and second reservoir 420 can beintegrally formed with one another as a single element, and anintegrally formed cover suitably can be attached to such element so asto provide upper surfaces of sample reservoir 416, plasma reservoir 417,and second reservoir 420, e.g., in a manner similar to that describedwith reference to FIG. 2B. Optionally, sample reservoir 416, plasmareservoir 417, and second reservoir 420 are arranged linearly with oneanother, e.g., such as illustrated in FIGS. 4A-4B.

The cover of device 400, which can form the upper surfaces of the firstand second reservoirs 410, 420, optionally can include first aperture(inlet port) 413 via which sample reservoir 416 can receive the sampleof whole blood, and/or second aperture 414 (outlet port) via which thefirst fraction can be withdrawn. First aperture 413 optionally can bedisposed over sample reservoir 416 and configured similarly as firstaperture (inlet port) 113 described with reference to FIGS. 1A-1D.Optionally, second aperture 414 can be disposed over the plasmareservoir 417 and configured similarly as second aperture 413 describedwith reference to FIGS. 1A-1D. Alternatively, in the exemplaryconfiguration illustrated in FIG. 4A, device 400 optionally includeschannel 430 which is fluidically connected to the collection region 411,for example to plasma reservoir 417. Channel 430 optionally isconfigured to substantially fill with the first fraction via capillaryaction responsive to termination of the centrifugal force. In someconfigurations, optional channel 430 is configured to fluidicallyconnect outlet 414 to the collection region 411, and the first fractioncan be withdrawn from collection region 411 via channel 430 and outlet414. In other configurations, optional channel 430 is coupled to anotherdevice (not specifically illustrated) which can receive the firstfraction via the channel. Additionally, or alternatively, channel 430optionally is disposed at an acute angle relative to the collectionregion 411, which can inhibit red blood cells from entering the firstfraction within the channel. If present, each of first aperture 413 andsecond aperture 414 independently optionally can be configured toreceive a pipette tip. Additionally, or alternatively, the cover ofdevice 400 optionally includes vent 415 disposed over sample reservoir416 so as to provide an outlet for air that is displaced when depositinga sample of whole blood into sample reservoir 416. Additionally, oralternatively, the cover of device 400 optionally can be at leastpartially optically transparent, for example to facilitate visual oroptical analysis of the blood sample or fractions within the device.

In the exemplary configuration illustrated in FIGS. 4A-4B, therespective lower surface 418 of the plasma reservoir 417 optionally iscloser to the cover (not shown in FIG. 4B, but generally extending in aplane immediately above first and second reservoirs 410, 420) than arethe respective lower surfaces 441, 421 of the sample reservoir 416 andsecond reservoir 420. Optionally, an upper surface (exemplary levelindicated with dotted lines in FIG. 4B) of the sample of whole blooddisposed within the sample reservoir 420 is further from the cover thanis the lower surface 418 of plasma reservoir 417. As such, when thesample of whole blood initially is deposited within sample chamber 416,the sample remains within that chamber under the force of gravity untilcentrifugal force is applied. Then, responsive to the centrifugal forceapplied to device 400, the sample of whole blood disposed within samplereservoir 416 flows upward toward the cover to contact lower surface 418of plasma reservoir 417. For example, optionally a first one of thesidewalls 419 of sample reservoir 416 can be disposed at an obtuse anglerelative to lower surface 441 of the sample reservoir. Responsive to thecentrifugal force applied to device 400, substantially all of the sampleof whole blood disposed within sample reservoir 416 flows upward alongsidewall 419 of the sample reservoir, e.g., to contact lower surface 418of plasma reservoir 417. As a further option, responsive to thecentrifugal force applied to device 400, a portion of the sample ofwhole blood contacting the lower surface 418 of plasma reservoir 417flows downward away from the cover to contact lower surface 421 ofsecond reservoir 420. For example, responsive to the centrifugal forceapplied to device 400, the portion of the sample of whole bloodcontacting lower surface 418 of plasma reservoir 417 flows downwardalong a first one of the sidewalls 422 of second reservoir 420.

In a manner similar to that described with reference to FIGS. 1A-1D, insome configurations the first and second fractions each contact thecover of device 400 after termination of the centrifugal force.Additionally, or alternatively, optionally the first fraction cansubstantially fill plasma reservoir 417 responsive to the centrifugalforce, e.g., in a manner similar to that described with reference toFIGS. 1A-1D. Additionally, or alternatively, optionally the secondfraction substantially fills second reservoir 420 responsive to thecentrifugal force, e.g., in a manner similar to that described withreference to FIGS. 1A-1D. Additionally, or alternatively, optionally ameniscus of the first fraction is disposed within the collection region,e.g., in a manner similar to that described with reference to FIGS.1A-1D. For example, meniscus 133 can extend between the upper and lowersurfaces of collection region 411, e.g., within plasma reservoir 417 ina manner similar to that described with reference to FIG. 1D.

As noted elsewhere herein, centrifugal force can be applied to thepresent devices so as to separate a sample of whole blood into the firstand second fractions. For example, FIG. 5 schematically illustrates aplan view of a disc including the device 400 of FIGS. 4A-4B, accordingto various configurations provided herein. The rotatable disc in whichfirst and second reservoirs are disposed, can be spun at any suitablerate, and for any suitable amount of time, so as to generate the firstand second fractions in a manner such as exemplified herein. Note thatalthough disc 500 specifically illustrated in FIG. 5 includes the device400 of FIGS. 4A-4B, disc 500 instead can include any other deviceprovided herein, such as any of devices 100, 200, 200′, 200″, 200′″,300, or 400.

FIG. 6 illustrates an exemplary flow of operations in a method of usingthe devices of FIGS. 1A-5 , and FIGS. 7A-7D schematically illustrateplan views of components of a blood plasma separation device duringoperations of the method of FIG. 6 , according to various configurationsprovided herein. Method 600 illustrated in FIG. 6 can include receiving,by a first reservoir of a device, a sample of whole blood comprising redblood cells (610). The first reservoir can include a collection regionand a constricted region, e.g., in a manner such as described withreference to the first reservoirs of any of devices 100, 200, 200′,200″, 200′″, 300, or 400. For example, in the nonlimiting exampleillustrated in FIG. 7A, the first reservoir can include sample reservoir416 and plasma reservoir 417 fluidically connected to one another,wherein sample reservoir 416 includes inlet 413 configured to receivethe sample of whole blood and plasma reservoir 417 includes thecollection region and the constricted region. Sample chamber 416 can befilled with a sample of whole blood through optional inlet port 413 orother suitable structure.

Method 600 illustrated in FIG. 6 can include applying a centrifugalforce to the device to separate the sample of whole blood into a firstfraction and a second fraction (620). The first fraction can be locatedin the collection region and including blood plasma from whichsubstantially all red blood cells have been removed. The second fractioncan be located in a second reservoir of the device and comprising bloodplasma and red blood cells that have been removed from the firstfraction by the centrifugal force. The constricted region can inhibitthe second fraction from entering the collection region. For example, inthe nonlimiting example illustrated in FIG. 7B, as a disc or otherstructure including the device (e.g., disc 500) begins to spin togenerate centrifugal force, the sample of whole blood migrates tosubstantially fill second reservoir 420 and plasma reservoir 417. Forexample, responsive to the centrifugal force, the sample of whole blooddisposed within sample reservoir 416 flows upward toward the cover tocontact lower surface 418 of plasma reservoir 417. Illustratively, in amanner such as described with reference to FIGS. 4A-4B, a first one ofthe sidewalls 419 of sample reservoir 416 can be disposed at an obtuseangle relative to the lower surface of the sample reservoir, andresponsive to the centrifugal force applied to the device, substantiallyall of the sample of whole blood disposed within sample reservoir 416flows upward along the first one of the sidewalls 419 of samplereservoir 416. Further, in a manner such as described with reference toFIGS. 4A-4B, optionally responsive to the centrifugal force applied tothe device, a portion of the sample of whole blood contacting lowersurface 418 of plasma reservoir 417 flows downward away from the coverto contact lower surface 421 of second reservoir 420, e.g., downwardalong a first one of the sidewalls 422 of the second reservoir.

After continuing to spin the disc or other structure including thedevice at a suitable rate and for a suitable amount of time,substantially all red blood cells within the sample of whole blood forma pellet in second reservoir 420 to form a second fraction, and bloodplasma from which substantially all red blood cells have been removedforms a first fraction that substantially fills plasma reservoir 417,such as illustrated in FIG. 7C. For example, the first fractionoptionally substantially fills plasma reservoir 417 responsive to thecentrifugal force, and/or the second fraction substantially fills secondreservoir 420 responsive to the centrifugal force. At least 75%, atleast 99%, or even 100% of the red blood cells in the sample of wholeblood optionally can be removed from the first fraction.

Method 600 illustrated in FIG. 6 optionally includes removing the firstfraction from the collection region. For example, optionally an outletfluidically connects to the collection region (e.g., to plasma reservoir417), such as outlet port (aperture) 414 illustrated in FIGS. 4A-4B and7D, or outlet port 114 illustrated in FIGS. 1A-1D, or outlet port 314illustrated in FIG. 3 . As a further option, a channel fluidicallyconnects the outlet to the collection region, such as channel 330illustrated in FIG. 3 or channel 414 illustrated in FIGS. 4A-4B and 7D.In a manner such as described elsewhere herein, the channel optionallycan be disposed at an acute angle relative to the collection region. Asillustrated in FIG. 7D, the channel optionally substantially fills withthe first fraction via capillary action responsive to termination of thecentrifugal force. Additionally, or alternatively, the first and secondfractions each optionally can contact the cover of the device aftertermination of the centrifugal force.

In some configurations, the present devices and methods are based oncentrifugal separation of whole blood into red blood cell and plasmacomponents, which respectively can be referred to herein as second andfirst fractions. The present devices optionally can sit radially on adisc, e.g., such as illustrated in FIG. 5 , in which whole blood can beloaded through an inlet port (fill hole) into a first reservoir, such asa sample reservoir (fill chamber) which can be closer to the center ofthe disc than are other components of the present devices. In onenonlimiting example, the sample reservoir includes a 5 mm deep areadesigned to hold sufficient volume based on a 110 μL sample size, forexample to inhibit or prevent spillage of the blood either into theoptional outlet channel during fill, or into the fill and outlet holdsduring spin start. As the disc is accelerated, blood transfers towardsthe outside (circumference) of the disc, filling the second reservoirwhich in one nonlimiting example includes a 5 mm deep chamber at thebottom of the design, as well as the plasma reservoir/collection regionwhich in one nonlimiting example is in the middle of the design. Therelatively low depth (shallowness) of the plasma reservoir can inhibitor prevent collapse of the plasma-air interface after spinning hasstopped, such that a meniscus of the plasma can remain within the plasmareservoir in a manner similar to that illustrated in FIG. 1D. Asspinning continues, plasma and red blood cells separate based oncentrifugal forces. Optionally, the second reservoir can be designedsuch that it can contain more than about 60.9% volume of a 110 μL loadedblood. The 60.9% hematocrit level (“worst case hematocrit”) representsaverage hematocrit plus 3 standard deviations, which should account for99.7% of the population. Therefore, in some configurations substantiallyall of the red blood cells become disposed in the second reservoir as aresult of the centrifugal forces, and blood plasma from whichsubstantially all of the red blood cells have been removed becomesdisposed in the collection region of the first reservoir (plasmareservoir). As the disc stops spinning, plasma gets drawn into an outletchannel (which can have an exemplary cross-sectional area of about 0.5mm by 0.5 mm) via capillary force, thus allowing for an air-freeaspiration of plasma from an outlet port coupled to, e.g., positionedabove, the outlet channel. In some configurations, the only vent duringaspiration of the plasma is the inlet port, allowing fluid to becollected until air connects the inlet and outlet ports to one anotherwithin the device (referred to as airknifing). Such airknifing togetherwith the constriction region can stabilize the red blood cells withinthe second reservoir and allow retrieval of substantially only the firstfraction without reintroduction of red blood cells from the secondfraction.

The present devices can be constructed using any suitable materials orcombination of materials, such as any suitable combination of polymer,glass, metal, and semiconductor. Additionally, the present devices canbe constructed using any suitable fabrication technique(s), such asmolding, 3D printing, machining, using laminate assemblies,thermoforming, chemical or laser etching, casting, and/or hot embossing.

In the descriptions above and in the claims, phrases such as “at leastone of” or “one or more of” may occur followed by a conjunctive list ofelements or features. The term “and/or” may also occur in a list of twoor more elements or features. Unless otherwise implicitly or explicitlycontradicted by the context in which it is used, such a phrase isintended to mean any of the listed elements or features individually orany of the recited elements or features in combination with any of theother recited elements or features. For example, the phrases “at leastone of A and B;” “one or more of A and B;” and “A and/or B” are eachintended to mean “A alone, B alone, or A and B together.” A similarinterpretation is also intended for lists including three or more items.For example, the phrases “at least one of A, B, and C;” “one or more ofA, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, Balone, C alone, A and B together, A and C together, B and C together, orA and B and C together.” In addition, use of the term “based on,” aboveand in the claims is intended to mean, “based at least in part on,” suchthat an unrecited feature or element is also permissible.

The subject matter described herein can be embodied in systems,apparatus, methods, and/or articles depending on the desiredconfiguration. The implementations set forth in the foregoingdescription do not represent all implementations consistent with thesubject matter described herein. Instead, they are merely some examplesconsistent with aspects related to the described subject matter.Although a few variations have been described in detail above, othermodifications or additions are possible. In particular, further featuresand/or variations can be provided in addition to those set forth herein.For example, the implementations described above can be directed tovarious combinations and subcombinations of the disclosed featuresand/or combinations and subcombinations of several further featuresdisclosed above. In addition, the logic flows depicted in theaccompanying figures and/or described herein do not necessarily requirethe particular order shown, or sequential order, to achieve desirableresults. Other implementations may be within the scope of the followingclaims.

What is claimed is:
 1. A device for separating blood plasma from wholeblood, the device comprising: a first reservoir configured to receive asample of whole blood comprising red blood cells, the first reservoircomprising: a collection region; a channel fluidly connecting thecollection region to an outlet; and a constricted region; and a secondreservoir fluidically connected to the constricted region of the firstreservoir, wherein: responsive to centrifugal force applied to thedevice, the sample of whole blood disposed within the first reservoirseparates into a first fraction and a second fraction, the firstfraction being located in the collection region and comprising bloodplasma from which substantially all red blood cells have been removed,the second fraction being located in the second reservoir and comprisingblood plasma and red blood cells that have been removed from the firstfraction by the centrifugal force, the channel is configured tosubstantially fill with the first fraction via capillary actionresponsive to termination of the centrifugal force, and the constrictedregion inhibits the second fraction from entering the collection region.2. The device of claim 1, wherein the channel is disposed at an acuteangle relative to the collection region.
 3. The device of claim 1,wherein the first reservoir comprises a sample reservoir and a plasmareservoir fluidically connected to one another, the sample reservoircomprising an inlet configured to receive the sample of whole blood, theplasma reservoir comprising the collection region and the constrictedregion.
 4. The device of claim 3, wherein the sample reservoir, plasmareservoir, and second reservoir each comprises one or more respectivesidewalls and a respective lower surface.
 5. The device of claim 4,wherein a cover is disposed over the sample reservoir, plasma reservoir,and second reservoir.
 6. The device of claim 5, wherein the respectivelower surface of the plasma reservoir is closer to the cover than arethe respective lower surfaces of the sample reservoir and the secondreservoir.
 7. The device of claim 6, wherein an upper surface of thesample of whole blood disposed within the sample reservoir is furtherfrom the cover than is the lower surface of the plasma reservoir.
 8. Thedevice of claim 7, wherein responsive to the centrifugal force appliedto the device, the sample of whole blood disposed within the samplereservoir flows upward toward the cover to contact the lower surface ofthe plasma reservoir.
 9. The device of claim 8, wherein: a first one ofthe sidewalls of the sample reservoir is disposed at an obtuse anglerelative to the lower surface of the sample reservoir, and responsive tothe centrifugal force applied to the device, substantially all of thesample of whole blood disposed within the sample reservoir flows upwardalong the first one of the sidewalls of the sample reservoir.
 10. Thedevice of claim 8, wherein responsive to the centrifugal force appliedto the device, a portion of the sample of whole blood contacting thelower surface of the plasma reservoir flows downward away from the coverto contact the lower surface of the second reservoir.
 11. The device ofclaim 10, wherein responsive to the centrifugal force applied to thedevice, the portion of the sample of whole blood contacting the lowersurface of the plasma reservoir flows downward along a first one of thesidewalls of the second reservoir.
 12. The device of claim 5, whereinthe first and second fractions each contact the cover after terminationof the centrifugal force.
 13. The device of claim 5, wherein the coveris at least partially optically transparent.
 14. The device of claim 5,wherein the cover comprises: a first aperture via which the samplereservoir receives the sample of whole blood; and a second aperture viawhich the first fraction is withdrawn.
 15. The device of claim 14,wherein the first aperture is disposed over the sample reservoir. 16.The device of claim 15, wherein the second aperture is disposed over theplasma reservoir.
 17. The device of claim 15, wherein the secondaperture is located over the channel.
 18. The device of claim 14,wherein the first and second apertures each are configured to receive apipette tip.
 19. The device of claim 5, wherein the cover furthercomprises a vent disposed over the sample reservoir.
 20. The device ofclaim 3, wherein the first fraction substantially fills the plasmareservoir responsive to the centrifugal force.
 21. The device of claim3, wherein the second fraction substantially fills the second reservoirresponsive to the centrifugal force.
 22. The device of claim 3, whereinthe sample reservoir, the plasma reservoir, and the second reservoir arearranged linearly with one another.
 23. The device of claim 3, wherein ameniscus of the first fraction is disposed within the collection region.24. The device of claim 1, wherein at least 75% of the red blood cellsin the sample of whole blood are removed from the first fraction. 25.The device of claim 1, wherein at least 99% of the red blood cells inthe sample of whole blood are removed from the first fraction.
 26. Thedevice of claim 1, wherein 100% of the red blood cells in the sample ofwhole blood are removed from the first fraction.
 27. The device of claim1, wherein the first reservoir has a volume about 25 μL to about 1 mL,or about 50-500 μL, or about 100-250 μL.
 28. The device of claim 1,wherein second reservoir has a volume of about 20-80% of a volume of thefirst reservoir, or a volume of about 40-60% of a volume of the firstreservoir.
 29. The device of claim 1, further comprising a rotatabledisc in which the first and second reservoirs are disposed.
 30. Anapparatus comprising: a first reservoir having a collection region andconstriction means configured to receive a sample of whole bloodcomprising red blood cells, and having a channel fluidly connecting thecollection region to an outlet; a second reservoir fluidically connectedto the constriction means, wherein: responsive to centrifugal forceapplied to the apparatus, the sample of whole blood disposed within thefirst reservoir separates into a first fraction and a second fraction,the first fraction being located in the collection region and comprisingblood plasma from which substantially all red blood cells have beenremoved, the second fraction being located in the second reservoir andcomprising blood plasma and red blood cells that have been removed fromthe first fraction by the centrifugal force, the channel is configuredto substantially fill with the first fraction via capillary actionresponsive to termination of the centrifugal force, and the constrictionmeans inhibit the second fraction from entering the collection region.